1. Technical Field
The present invention relates to a manufacturing method of a printed circuit board.
2. Description of the Related Art
At present, in manufacturing a rigid substrate, a copper clad laminate (CCL) is commonly used as a core material. With a method of laminating layers on the copper clad laminate, a multi-layer substrate is manufactured. Here, the copper clad laminate signifies a material made of an insulator 1 added by a glass fiber, etc., having copper foils 2 formed on both sides thereof, as shown in FIG. 1.
Recently, with increasing demands for portable, light and thin electronic devices having many abilities, a thin printed circuit board having high density is also increasingly required.
For that reason, a plating method using a seed layer is widely used as a method of implementing a high density circuit.
FIGS. 1 to 7 show a manufacturing method of a printed circuit board according to a related art. Referring to FIGS. 1 to 7, illustrated are an insulator 1, a copper foil 2, a via hole 3, a seed layer 4, a plating resist 5, a via 6 and patterns 7 and 8. A manufacturing method of a printed circuit board according to the related art will be concisely described below
First, as shown in FIG. 1, prepared is a copper clad laminate made of an insulator 1 having copper foils 2 formed on both sides thereof, and then a via hole 3 is processed as shown in FIG. 2. A mechanical drill or a laser drill is used as a method of processing the via hole 3.
As shown in FIG. 3, a seed layer 4 is formed on the inner wall of the via hole 3 and on the surface of the copper foil 2, and then a plating resist 5 is formed as shown in FIG. 4. Subsequently, electrolytic plating is performed as shown in FIG. 5.
A printed circuit board having a predetermined via 6 and patterns 7 and 8 formed therein can be manufactured by removing the plating resist 5 as shown in FIG. 6 and a part of the seed layer 4 through a flash etching as shown in FIG. 7.
However, according to the related art, when a plating is performed in order to form the via 6, and the patterns 7 and 8, the thickness of the plated material is not uniform. Such a thickness difference becomes larger when the lower copper foil 2 is damaged during the via hole 3 processing as shown in FIG. 2.
Besides, since there is a case where an excessive etching is processed lest the seed layer 4 should remain when removing the seed layer 4, the pattern may have a possibility of occurrence of more excessive thickness deviation. Due to the reason, it is difficult to form a pattern having a thickness desired by a user.